Eosinophilic esophagitis (EoE, also referred to as EE in some publications) is a recently identified clinico-pathological gastrointestinal (GI) allergic disease characterized by pronounced eosinophil infiltration locally restricted in the esophagus. EoE is often defined based upon an artificial threshold of >15 eosinophils/HPF in patients who have had acid-induced esophageal injury excluded as a cause for the esophageal histology (Furuta, et al. Gastroenterology 133:1342-63 (2007)). It has been estimated that nearly 1:1000 individuals in the western world may have EoE, which likely accounts for the approximately 10-30% of chronic esophagitis cases that are found to be refractory to proton pump inhibitor (PPI) therapy.
The treatment of EoE is distinct from other forms of esophagitis, as effective management depends upon elimination of the triggering food types or the usage of anti-inflammatory medications (e.g. glucocorticoids). Accordingly, it is important to differentiate EoE from other gastrointestinal afflictions, such as gastroesophageal reflux disease (GERD). Unfortunately, EoE diagnosis relies upon histological analysis of esophageal biopsies, which requires the uncomfortable procurement of up to 5 biopsies to obtain sufficient sensitivity for diagnosis of the disease. In addition, a histological finding is not specific for EoE, as it is determined by methods that depend upon variable biopsy procurement and subjective microscopic review of biopsies and features that can be common to other esophageal disorders. This is because esophageal eosinophilia is not specific to EoE, as eosinophil migration into the esophagus also occurs in other disease processes, including GERD, infections, and auto-immune diseases, which complicates diagnosis based upon eosinophil detection. Furthermore, exposure to specific drugs, especially anti-inflammatory agents, which can affect tissue histology, cannot be directly derived by microscopic analysis of biopsy specimens (Rodrigo, et al. Am. J. Gastroenterol. 103:435-42 (2008)).
Accordingly, there is a need for development of diagnostic procedure options that are fast, efficient, inexpensive, and able to improve the diagnostic specificity for EoE. Such methods ideally can also be used to distinguish EoE over other esophageal disorders.